Britain sustained its first Islamic terrorist attack in July 2005 when I was responsible for coordinating the national intelligence agencies in support of COBRA.

Following COBRA’s meeting on the day of the London attack this week, the emergency committee will have met several times.

One of the key issues under discussion has been the profile of the terrorist, his known associates and whether he was working alone.

The members of COBRA would have quickly realized that 52-year-old Khalid Masood did not fit the usual profile for jihadists active in this country.

The average age is just 22 – often impressionable hotheads who are easy prey for radical preachers like Anjem Choudhray, himself now in prison for terror-related crimes.

Masood seems to come from a relatively well-to-do background. This is not uncommon, contrary to the popular misconception that most jihadists are from poor families, marginalized and cast aside by society.

He had been in several prisons, and it is very likely that the Christian convert was radicalized while inside. Disgracefully, our prisons remain a breeding ground for Islamic extremism.

His crimes, over 20 years, had involved violent assault, public order and possession of offensive weapons.

He had no terrorist convictions. But like many others who have launched attacks in Europe, Masood had previously come to the intelligence services’ attention on the margins of a terrorist investigation.

He was no longer a suspect and not under surveillance. The reality is MI5 and the police cannot monitor everyone they believe to be involved in Islamic terrorist activity.

There are just too many for them to cope with. The Head of MI5 says his service knows of 3,000 jihadists in the UK. Such a huge number cannot possibly be monitored.

On top of these, with the Islamic State under pressure in Syria and Iraq, hundreds of British citizens who have fought with this murder gang will return home.

Plus even known jihadists from European countries will continue to be free to travel to Britain until we leave the EU.

Allowing such freedom of movement in the name of the human rights of known terrorists puts all of our citizens in mortal danger.